CN109111574B

CN109111574B - Preparation method of Si-Al-C-O fiber

Info

Publication number: CN109111574B
Application number: CN201810605148.6A
Authority: CN
Inventors: 刘玉付; 储昭杰
Original assignee: Southeast University
Current assignee: Southeast University
Priority date: 2018-06-12
Filing date: 2018-06-12
Publication date: 2021-04-06
Anticipated expiration: 2038-06-12
Also published as: CN109111574A

Abstract

A preparation method of Si-Al-C-O fiber. The invention discloses a preparation method of polyaluminum carbosilane, which comprises the following steps: uniformly mixing the polycarbosilane solution and the 8-hydroxyquinoline aluminum solution, reacting for 0.5-2 h at the temperature of 230-300 ℃ and the pressure of 0.5-2 MPa, and distilling. The invention also discloses a method for further processing the polyaluminocarbosilane prepared by the method to prepare the Si-Al-C-O fiber. Compared with the precursor synthesized by normal pressure and high temperature solid phase, the precursor containing aluminum prepared by the method is more uniform, the aluminum content is controllable, the synthesis process is simpler, and the safety is high; the synthesized aluminum-containing precursor has high softening point, good spinnability, high spinning stability and high yield after high-temperature sintering; the prepared Si-Al-C-O fiber is smooth, black and bright; the average diameter is fine; the average tensile strength is high, and various properties are stable; can be directly used as a reinforcement to be used in high temperature resistant materials, and can also be further sintered at ultrahigh temperature to obtain the polycrystalline Si-Al-C fiber.

Description

Preparation method of Si-Al-C-O fiber

Technical Field

The invention belongs to the field of ceramic fiber materials, and particularly relates to a preparation method of a Si-Al-C-O ceramic fiber material.

Technical Field

The continuous thin-diameter SiC fiber has excellent performances of high strength (1-4 GPa), high modulus (150-400 GPa), high temperature resistance (more than 1000 ℃), oxidation resistance, creep resistance and the like, and is an ideal reinforcing (toughening) body of the high-performance ceramic matrix composite material. The aluminum-containing SiC fiber has outstanding high temperature resistance, can resist high temperature of over 1800 ℃ and has wide application in the high temperature field.

More scientific institutions and companies research the aluminum-containing SiC fibers. Tyranno SA fibers researched by Ishikawa et al (Ishikawa T, Kohtoku Y, Kumagawa K, et al, high-strand h alkali-resistant sintered SiCfiber stable to2,200 ℃ [ J ]. Nature.1998.391 (6669): 773-775.) in Japan have excellent properties in all aspects, have tensile strength of more than 2.5GPa and modulus of more than 300GPa, can keep the mechanical properties of 1900 ℃ and have small reduction of tensile strength even if heat treated at 2000 ℃ for 1 hour in argon atmosphere, and still keep 80 percent of tensile strength, thus being the SiC fibers with the best high-temperature resistance at present. However, the aluminum source of the aluminum acetylacetonate is easy to volatilize during synthesis at 300 ℃, so that the aluminum content is difficult to control.

Yuyu seal proposes that poly-silicon carbosilane (PSCS) and aluminum acetylacetonate are used as raw materials, aluminum-containing precursor poly-aluminum carbosilane is synthesized by a normal-pressure high-temperature method, Si-A1-C-O fiber with higher performance, namely KD-A fiber, is prepared by melt spinning of the aluminum-containing precursor, air infusible treatment and exploration of a high-temperature sintering process, and the KD-SA fiber with excellent high-temperature resistance is finally prepared by ultrahigh-temperature sintering (Yuyu seal, continuous preparation and research of aluminum-containing silicon carbide fiber [ D ]. Changsha: aerospace and materials engineering college of national defense science and technology, 2005.). However, the performance of the fiber is different from that of Tyranno SA fiber, and the preparation process has some problems, mainly reflected in that: the synthesis of the aluminum-containing precursor is not stable enough, the uniformity is poor, particularly, the aluminum content distribution range of the aluminum-containing precursor synthesized in different batches is large and is between 0.25 and 0.7 weight percent, and the yield is low; the synthesis process is complex and tedious, and the conditions are not easy to control; poor spinning stability, etc. The average diameters of the prepared KD-A fiber and KD-SA fiber are thicker and are respectively in the ranges of 12-14 mu m and 10-12 mu m; the average tensile strength of the KD-SA fiber is 2.0-2.6 GPa, and the KD-SA fiber is different from the Tyranno SA fiber.

In addition, Chenjiang river synthesizes polyaluminium carbosilane by using Polydimethylsiloxane (PDMS) and aluminum acetylacetonate as raw materials (Chenjiang river, synthesis and characterization of organosilicon polymers for silicon carbide-based ceramic fibers [ D ]. Xiamen: college of chemistry and chemical industry of Xiamen university, 2007.), Yanjing Ming synthesizes polyaluminium carbosilane by using Liquid Polycarbosilane (LPCS) and aluminum acetylacetonate as raw materials (Yanjing, Yanglu flood, Yunhuang, and the like. Synthesis and characterization of polyaluminium carbosilane based on liquid polycarbosilane [ J ]. advanced school chemistry report, 2009, 30 (12): 2525-2529.), but reports on aluminum-containing SiC fibers are few. Shenjie synthesizes an aluminum-containing precursor with controllable aluminum content through normal-pressure high-temperature reaction (Shenjie, preparation and performance research of aluminum-containing silicon carbide fiber [ D ]. Nanjing, university of southeast university college of materials science and engineering, 2017.), but the synthesized aluminum-containing precursor has poor uniformity and spinnability, spinning is not very stable, and the prepared aluminum-containing SiC fiber has low tensile strength.

In conclusion, the existing method is difficult to prepare the aluminum-containing precursor polyaluminum carbosilane which has the advantages of uniformity, controllable aluminum content, high softening point, good spinning performance and high yield, and the Si-Al-C-O fiber with high performance is prepared by melt spinning, air non-melting treatment and high-temperature sintering.

Disclosure of Invention

The invention aims to provide the preparation method of the polyaluminum carbosilane, which has the advantages of good uniformity, controllable aluminum content, high softening point, good spinnability, stable spinning property, simple synthesis process and high safety.

The invention also aims to provide a preparation method of the Si-Al-C-O fiber with excellent performance aiming at the problems of complex and fussy synthesis process of the aluminum-containing precursor, poor product uniformity, uncontrollable aluminum content, difficult control of technological conditions of melt spinning, air infusible treatment, high-temperature sintering and the like in the process of preparing the aluminum-containing SiC fiber by a precursor conversion method.

The technical scheme is as follows: the invention provides a preparation method of polyaluminum carbosilane, which comprises the following steps: uniformly mixing the polycarbosilane solution and the 8-hydroxyquinoline aluminum solution, reacting for 0.5-2 h at the temperature of 230-300 ℃ and the pressure of 0.5-2 MPa, and distilling to remove the solvent to obtain the aluminum-containing precursor polyaluminum carbosilane.

Preferably, the reaction is carried out in a reaction kettle, and the mass ratio of the added polycarbosilane to the 8-hydroxyquinoline aluminum is 15-100: 1; the solvent in the polycarbosilane solution is preferably xylene, the solvent in the 8-hydroxyquinoline aluminum solution is preferably N, N-dimethylformamide, and the dissolving temperature of the polycarbosilane and the 8-hydroxyquinoline aluminum is 50-70 ℃.

The polyaluminocarbosilane prepared by the method is transparent faint yellow resin, the softening point is high and is 240-290 ℃, and the yield is high and is 67-73% after air non-melting treatment and high-temperature sintering.

In another aspect, the present invention provides a method for preparing Si-Al-C-O fiber, comprising the steps of:

1) preparing polyaluminum carbosilane by the method;

2) carrying out melt spinning on the polyaluminium carbosilane prepared in the step 1) to obtain precursor fiber protofilament containing aluminium;

3) carrying out air infusible treatment on the precursor fiber protofilament containing aluminum prepared in the step 2);

4) and 3) firing the precursor fiber protofilament containing aluminum after the air infusibility treatment in the step 3) to obtain the Si-Al-C-O fiber.

In the step 2), the temperature of melt spinning is 320-350 ℃, the pressure is 0.4-1.2 MPa, the spinning speed is 800-1200 r/min, and the continuous spinning length reaches 1734 m; in the step 3), the aluminum-containing precursor fiber precursor is subjected to air infusible treatment at the temperature of 160-220 ℃ for 5-16 h; in step 4), under the pressure of less than 10^-2Pa, sintering the precursor fiber precursor containing aluminum for 0.5 to 1 hour under the temperature of 950 to 1200 ℃.

The fiber prepared by the method has smooth surface and no obvious defects such as holes, cracks, grooves and the like; the fiber diameter is small and is 8.0-12 mu m; the tensile strength is 1.3-2.9 GPa.

In addition, the aluminum-containing precursor polyaluminum carbosilane can also be applied to preparation of silicon carbide films, silicon carbide pattern layers, substrates of silicon carbide composite materials, high-temperature binders and the like.

Has the advantages that: the method comprises the steps of taking 8-hydroxyquinoline aluminum with a high melting point as an aluminum source and polycarbosilane as raw materials, enabling the polycarbosilane and the 8-hydroxyquinoline aluminum to react in a liquid phase under the condition of high temperature and high pressure generated by a reaction kettle to prepare aluminum-containing precursor polyaluminum carbosilane with a high softening point, carrying out melt spinning on the aluminum-containing precursor to obtain fiber precursors, carrying out air-infusible treatment on the fiber precursors, and finally carrying out high-temperature firing to obtain the Si-Al-C-O fiber. Compared with the precursor synthesized by normal-pressure high-temperature solid phase, the synthesized aluminum-containing precursor is more uniform, the aluminum content is controllable, and meanwhile, the synthesis process is simpler and has high safety; the synthesized aluminum-containing precursor has high softening point, good spinnability, high spinning stability and high yield after high-temperature sintering; the prepared Si-Al-C-O fiber is smooth, black and bright; the average diameter is fine; the average tensile strength is high, and various properties are stable; the high-temperature-resistant polycrystalline Si-Al-C fiber can be directly used as a reinforcement to be used in a high-temperature-resistant material, and can be further sintered at ultrahigh temperature to obtain a near-stoichiometric-ratio polycrystalline Si-Al-C fiber with more excellent high-temperature resistance.

Drawings

FIG. 1 is a photograph of an aluminum-containing precursor synthesized in example 1;

FIG. 2 is a photograph of a fiber strand prepared by melt spinning the aluminum-containing precursor synthesized in example 1;

FIG. 3 is an SEM image of Si-Al-C-O fiber prepared by melt spinning, air-infusible treatment and high-temperature firing of the aluminum-containing precursor synthesized in example 1;

FIG. 4 is an SEM image and an EDS energy spectrum of Si-Al-C-O fibers prepared by melt spinning, air-infusible treatment and high-temperature sintering of the aluminum-containing precursor synthesized in example 1;

FIG. 5 is an SEM image of Si-Al-C-O fiber prepared by melt spinning, air-infusible treatment and high-temperature firing of the aluminum-containing precursor synthesized in example 2;

FIG. 6 is a graph showing the tensile strength distribution of Si-Al-C-O fibers prepared by melt-spinning the aluminum-containing precursor synthesized in example 3, air-insolubilizing, and pyrolyzing the precursor for 30min at different temperatures: wherein, (a) corresponds to a Si-Al-C-O fiber tensile strength distribution diagram prepared by pyrolysis at 950 ℃ for 30 min; (b) correspondingly, the tensile strength distribution diagram of the Si-Al-C-O fiber prepared by pyrolysis at 1000 ℃ for 30 min; (c) the corresponding is the tensile strength distribution diagram of the Si-Al-C-O fiber prepared by pyrolysis at 1050 ℃ for 30 min.

Detailed Description

The technical solutions of the present invention are further described below with reference to the drawings and the specific embodiments, but the scope of the present invention is not limited thereto.

Example 1

(1) Preparation of aluminium-containing precursor polyaluminocarbosilane

Dissolving 15.00g of Polycarbosilane (PCS) in dimethylbenzene at 60 ℃ to obtain a polycarbosilane solution; 1.00g of 8-hydroxyquinoline aluminum was dissolved in N, N-Dimethylformamide (DMF) to obtain an 8-hydroxyquinoline aluminum solution. Mixing the polycarbosilane solution and the 8-hydroxyquinoline aluminum solution to obtain a clear solution, transferring the clear solution into a reaction kettle, placing the reaction kettle into a high-temperature oven, heating to 280 ℃, preserving heat for 1h, and cooling to room temperature to obtain a solution of a synthesized product, wherein the pressure in the reaction kettle is 0.5-2 MPa in the reaction process; distilling to obtain yellowish transparent resin-like aluminum-containing precursor polyaluminum carbosilane as shown in FIG. 1.

(2) Preparation of Si-Al-C-O fiber

Heating the aluminum-containing precursor prepared in the step (1) by a single-hole spinning machine under the protection of argon, applying a pressure of 0.5MPa to enable the aluminum-containing precursor to flow out of a spinning opening and revolve to a graphite roller rotating at a high speed of 1000r/min, and obtaining an aluminum-containing precursor fiber precursor as shown in figure 2.

And putting the spun precursor fiber protofilament containing aluminum and the graphite roller into a blast oven, heating to 200 ℃, and preserving heat for 6 hours to obtain the infusible fiber protofilament. Then placing the fiber protofilament and the graphite roller which are not melted into a vacuum sintering furnace, vacuumizing, and when the pressure in the furnace body is less than 10^-2And when Pa is needed, heating to 1000 ℃, and pyrolyzing for 30min to obtain the Si-Al-C-O fiber.

The softening point of the aluminum-containing precursor polyaluminum carbosilane prepared by the embodiment is about 275 ℃, the continuous spinning time is 1-6 min, the continuous spinning length reaches 289-1734 m, and the yield of the sintered Si-Al-C-O fiber is 72.78%. The surface appearance and diameter distribution of the sintered Si-Al-C-O fiber are shown in figure 3, the average diameter of the Si-Al-C-O fiber is 10.3 mu m, the tensile strength is 1.3-2.6 GPa, and the average tensile strength is 1.7 GPa; the chemical composition of the fiber is shown in FIG. 4 by EDS spectroscopy, and the content of aluminum and the content of oxygen in the Si-Al-C-O fiber are respectively 0.47 wt% and 9.01 wt%.

Example 2

(1) Preparation of aluminium-containing precursor polyaluminocarbosilane

Dissolving 15.00g of Polycarbosilane (PCS) in dimethylbenzene to obtain a polycarbosilane solution; 1.00g of 8-hydroxyquinoline aluminum was dissolved in N, N-Dimethylformamide (DMF) to obtain an 8-hydroxyquinoline aluminum solution. Mixing the polycarbosilane solution and the 8-hydroxyquinoline aluminum solution to obtain a clear solution, transferring the clear solution into a reaction kettle, placing the reaction kettle into a high-temperature oven, heating to 280 ℃, preserving heat for 1h, keeping the pressure in the reaction kettle at 0.5-2 MPa in the reaction process, and cooling to room temperature to obtain a solution of a synthesized product; distilling to obtain the precursor polyaluminum carbosilane containing aluminum.

(2) Preparation of Si-Al-C-O fiber

And (2) under the protection of argon, heating the aluminum-containing precursor prepared in the step (1) to 343 ℃ by a single-hole spinning machine, applying pressure of 0.8MPa to enable the precursor to flow out of a spinning opening and rotate to a graphite roller rotating at a high speed of 1000r/min, and obtaining the precursor fiber precursor containing aluminum.

Putting precursor fiber protofilament containing aluminum and a graphite roller together into a drumAnd (4) heating to 200 ℃ in an air drying oven, and preserving heat for 9 hours to obtain the infusible fiber precursor. Fixing two ends of the fiber protofilament with graphite clamps, placing in a vacuum sintering furnace, vacuumizing, and keeping the pressure in the furnace less than 10^-2And when Pa is needed, heating to 1000 ℃, and pyrolyzing for 30min to obtain the Si-Al-C-O fiber.

In the embodiment, the continuous spinning time of the aluminum-containing precursor is 1-5 min, the continuous spinning length is 289-1445 m, the average diameter of the sintered Si-Al-C-O fiber is 8.3 μm, the tensile strength is 1.6-2.8 GPa, and the average tensile strength is 2.1GPa, as shown in FIG. 5.

Example 3

(1) Preparation of aluminium-containing precursor polyaluminocarbosilane

(2) Preparation of Si-Al-C-O fiber

And (2) under the protection of argon, heating the aluminum-containing precursor polyaluminum carbosilane prepared in the step (1) to 340 ℃ by a single-hole spinning machine, and applying pressure of 0.6MPa to enable the precursor to flow out of a spinning opening and revolve to a graphite roller rotating at a high speed of 1000r/min, so as to obtain the aluminum-containing precursor fiber precursor.

Putting the precursor fiber precursor containing aluminum and the graphite roller into a blast oven, heating to 220 ℃, and preserving heat for 5 hours to obtain the infusible fiber precursor. Fixing two ends of the fiber protofilament with graphite clamps, placing in a vacuum sintering furnace, vacuumizing, and keeping the pressure in the furnace less than 10^-2And when Pa is needed, heating to 950 ℃, 1000 and 1050 ℃ respectively for pyrolysis for 30min to obtain the Si-Al-C-O fiber.

The continuous spinning time of the aluminum-containing precursor in the embodiment is 1-4 min, and the continuous spinning length is 289-1156 m; the average diameter of the Si-Al-C-O fiber sintered under the three different temperature conditions is 9.5 μm, and the tensile strength distribution is shown in FIG. 6. Wherein (a) is a Si-Al-C-O fiber tensile strength distribution diagram prepared by pyrolysis at 950 ℃ for 30min, the tensile strength is 1.3-2.7 GPa, and the average tensile strength is 2.0 GPa; (b) the tensile strength distribution diagram of the Si-Al-C-O fiber prepared by pyrolysis at 1000 ℃ for 30min is that the tensile strength is 1.0-2.9 GPa, and the average tensile strength is 2.1 GPa; (c) the tensile strength distribution diagram of the Si-Al-C-O fiber prepared by pyrolysis at 1050 ℃ for 30min is that the tensile strength is 1.3-2.6 GPa, and the average tensile strength is 1.9 GPa.

Example 4

(1) Preparation of aluminium-containing precursor polyaluminocarbosilane

Dissolving 15.00g of Polycarbosilane (PCS) in dimethylbenzene to obtain a polycarbosilane solution; 1.00g of 8-hydroxyquinoline aluminum was dissolved in N, N-Dimethylformamide (DMF) to obtain an 8-hydroxyquinoline aluminum solution. Mixing the polycarbosilane solution and the 8-hydroxyquinoline aluminum solution to obtain a clear solution, and transferring the clear solution into a reaction kettle; placing the reaction kettle in a high-temperature oven, heating to 250 ℃, keeping the temperature for 2 hours, and cooling to room temperature to obtain a solution of a synthetic product, wherein the pressure in the reaction kettle is 0.5-2 MPa in the reaction process; distilling to obtain light yellow transparent resin-shaped aluminum-containing precursor polyaluminum carbosilane with a softening point of 270 ℃. The precursor containing aluminum is uniform and has excellent spinning performance.

(2) Preparation of Si-Al-C-O fiber

And (2) under the protection of argon, heating the aluminum-containing precursor prepared in the step (1) to 320 ℃ by using a single-hole spinning machine, applying 1.2MPa of pressure to enable the aluminum-containing precursor to flow out of a spinning opening and rotate to a 1200r/min high-speed rotating graphite roller, and obtaining the aluminum-containing precursor fiber precursor.

And putting the spun precursor fiber protofilament containing aluminum and the graphite roller into a blast oven, heating to 160 ℃, and preserving heat for 16 hours to obtain the infusible fiber protofilament. Then placing the fiber protofilament and the graphite roller which are not melted into a vacuum sintering furnace, vacuumizing, and when the pressure in the furnace body is less than 10^-2And when Pa is needed, heating to 1200 ℃, and pyrolyzing for 30min to obtain the Si-Al-C-O fiber.

Example 5

(1) Preparation of aluminium-containing precursor polyaluminocarbosilane

Dissolving 15.00g of Polycarbosilane (PCS) in dimethylbenzene to obtain a polycarbosilane solution; 1.00g of 8-hydroxyquinoline aluminum was dissolved in N, N-Dimethylformamide (DMF) to obtain an 8-hydroxyquinoline aluminum solution. Mixing the polycarbosilane solution and the 8-hydroxyquinoline aluminum solution to obtain a clear solution, and transferring the clear solution into a reaction kettle; placing the reaction kettle in a high-temperature oven, heating to 230 ℃, preserving heat for 1h, keeping the pressure in the reaction kettle at 0.5-2 MPa in the reaction process, and cooling to room temperature to obtain a solution of a synthetic product; distilling to obtain light yellow transparent resin-shaped aluminum-containing precursor polyaluminum carbosilane with a softening point of 270 ℃. The precursor containing aluminum is uniform and has excellent spinning performance.

(2) Preparation of Si-Al-C-O fiber

And (2) under the protection of argon, heating the aluminum-containing precursor prepared in the step (1) by a single-hole spinning machine to 350 ℃, applying pressure of 0.4MPa to enable the aluminum-containing precursor to flow out of a spinning opening and rotate to an graphite roller rotating at a high speed of 800r/min, and obtaining the aluminum-containing precursor fiber precursor with excellent performance.

And putting the spun precursor fiber protofilament containing aluminum and the graphite roller into a blast oven, heating to 180 ℃, and preserving heat for 16 hours to obtain the infusible fiber protofilament. Then placing the fiber protofilament and the graphite roller which are not melted into a vacuum sintering furnace, vacuumizing, and when the pressure in the furnace body is less than 10^-2And when Pa is needed, heating to 1200 ℃, and pyrolyzing for 30min to obtain the Si-Al-C-O fiber.

Example 6

(1) Preparation of aluminium-containing precursor polyaluminocarbosilane

Dissolving 15.00g of Polycarbosilane (PCS) in dimethylbenzene to obtain a polycarbosilane solution; 0.5g of 8-hydroxyquinolinylaluminum was dissolved in N, N-Dimethylformamide (DMF) to obtain an 8-hydroxyquinolinylaluminum solution. Mixing the polycarbosilane solution and the 8-hydroxyquinoline aluminum solution to obtain a clear solution, transferring the clear solution into a reaction kettle, placing the reaction kettle into a high-temperature oven, heating to 250 ℃, keeping the temperature for 1h, keeping the pressure in the reaction kettle at 0.5-2 MPa in the reaction process, and cooling to room temperature to obtain a solution of a synthesized product; distilling to obtain the low-aluminum-content aluminum-containing precursor polyaluminum carbosilane.

(2) Preparation of Si-Al-C-O fiber

And (2) under the protection of argon, heating the aluminum-containing precursor prepared in the step (1) by a single-hole spinning machine at 342 ℃, applying pressure of 0.5MPa to enable the aluminum-containing precursor to flow out of a spinning opening and rotate to a graphite roller rotating at a high speed of 1000r/min, and obtaining the aluminum-containing precursor fiber precursor.

Example 7

(1) Preparation of aluminium-containing precursor polyaluminocarbosilane

Dissolving 15.00g of Polycarbosilane (PCS) in dimethylbenzene to obtain a polycarbosilane solution; 0.25g of 8-hydroxyquinolinylaluminum was dissolved in N, N-Dimethylformamide (DMF) to give an 8-hydroxyquinolinylaluminum solution. Mixing the polycarbosilane solution and the 8-hydroxyquinoline aluminum solution to obtain a clear solution, transferring the clear solution into a reaction kettle, placing the reaction kettle into a high-temperature oven, heating to 250 ℃, keeping the temperature for 1h, keeping the pressure in the reaction kettle at 0.5-2 MPa in the reaction process, and cooling to room temperature to obtain a solution of a synthesized product; distilling to obtain the low-aluminum-content aluminum-containing precursor polyaluminum carbosilane.

(2) Preparation of Si-Al-C-O fiber

And putting the spun precursor fiber protofilament containing aluminum and the graphite roller into a blast oven, heating to 200 ℃, and preserving heat for 6 hours to obtain the infusible fiber protofilament. Then the fiber raw material which is not melted is treatedThe wire and the graphite roller are placed in a vacuum sintering furnace and vacuumized, and when the pressure in the furnace body is less than 10^-2And when Pa is needed, heating to 1000 ℃, and pyrolyzing for 30min to obtain the Si-Al-C-O fiber.

It should be understood that the above examples are only for clearly illustrating the present invention and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And such obvious variations or modifications which fall within the spirit of the invention are intended to be covered by the scope of the present invention.

Claims

1. A method for preparing polyaluminum carbosilane, comprising: uniformly mixing a polycarbosilane solution and an 8-hydroxyquinoline aluminum solution at 60 ℃, reacting for 0.5-2 h at the temperature of 230-300 ℃ and under the pressure of 0.5-2 MPa, and removing a solvent to obtain the polyaluminum carbosilane, wherein the softening point of the polyaluminum carbosilane is 240-290 ℃, the reaction is carried out in a reaction kettle, the mass ratio of the added polycarbosilane to the 8-hydroxyquinoline aluminum is 15-100: 1, the solvent in the polycarbosilane solution is xylene, and the solvent in the 8-hydroxyquinoline aluminum solution is N, N-dimethylformamide.

2. A preparation method of Si-Al-C-O fiber is characterized by comprising the following steps:

1) preparing a polyaluminocarbosilane using the method of claim 1;

2) carrying out melt spinning on the polyaluminum carbosilane prepared in the step 1) to obtain a polyaluminum carbosilane fiber precursor;

3) carrying out air infusible treatment on the poly-aluminum carbon silane fiber protofilament prepared in the step 2);

4) and (3) sintering the poly-aluminum carbon silane fiber protofilament subjected to the air infusibility treatment in the step 3) to obtain the Si-Al-C-O fiber.

3. The method for producing an Si-Al-C-O fiber according to claim 2, wherein in the step 2), the melt spinning temperature is 320 to 350 ℃ and the pressure is 0.4 to 1.2 MPa.

4. The preparation method of the Si-Al-C-O fiber according to claim 2, wherein in the step 3), the poly-aluminum carbon silane fiber precursor is subjected to air infusible treatment at 160-220 ℃ for 5-16 h.

5. The method for producing Si-Al-C-O fiber according to claim 2, wherein in the step 4), the pressure is less than 10^-2Pa, and the temperature is 950-1200 ℃ for 0.5-1 hour.